Originally Posted by Neutron
Here's my 10 gallon, newly re-done community with 3 females, 2 emerald cories and an oto. The bettas are sisters from the same tank and so far getting along great! Just picked them up today.
Pretty tank, and the 3 girls already been addressed.. one more concern is that you have pots on the bottom.. but girls in sororities require a lot of medium to tall plants rather then bottom cover... the lines of sight where they spend most of their time needs to be broken up in at least 3 different places- both in the middle and top of the tank, as well as back wall to front wall. Having too much open space such as that will cause a lot of aggression issues. Males tend to prefer the caves, but for sororities, you will need plant coverage rather then caves.
One way is best explained is if you are looking into the tank from the side, you shouldn't easily see the glass on the other side. Right now there may not be aggression, but once they are adjusted fully and such, they will start to seek out territories and that is when you may have issues.
By all means, keep those pretty pots in there, but you will definitely want to add a lot more tall plants to give the girls a chance at escaping and hiding and setting up territory.
As for your question.. you will want to take them all out of the tank, cup them, float them all together, rearrange the tank and let them out- since the 3 girls you have in there already is setting up their own spaces, it needs to look like a new tank for them.
That's just my opinion.. here are a couple pictures by a couple members here, and there are tons more- but this shows you the basics on how it should be covered. Otherwise, it is a lovely tank for a betta :)